An encryption communication network is known which is configured by a plurality of networked nodes connected to each other through a plurality of links. Each node has a function of generating and sharing a random number with an oppoising node connected through the link, and a function of performing encryption communication on the link using the random number as an encryption key (hereinafter, a link key). In addition, some of the nodes each have a function of generating a random number independently of the link, and a function of transmitting the generated random number to the other nodes. An application in the encryption communication network has a function of acquiring the random number from the node, and performing the encryption communication with another application using the random number as the encryption key (hereinafter, refer to as an application key). The application may be integrally implemented in the node, or may be implemented as a terminal independently of the node.
In the node, the function of generating and sharing the random number (the link key) between the oppoising nodes connected through the link, for example, is generally implemented by a technique called a quantum encryption communication. In this case, a technique of generating the random number (the application key) in the node independently of the link and transmitting the generated random number to another node through the link may be referred to as a quantum key distribution (QKD).
However, a specific sequence of generating of timing at which the random number (the application key) is generated independently of the link and a frequency thereof is not clearly disclosed in the conventional technique, so that it is difficult to efficiently generate and share the application key.